Codec deployment using in-band signals

ABSTRACT

After a call is established between two stations using a codec that has been negotiated during call setup, in-band signaling may be used between the two stations to change the codec that is to be used. The in-band signals are indicative that the station that is transmitting the in-band signals can operate with a second codec and are used to probe whether the receiving station can also operate with that second codec. If the receiving station detects and reacts to the in-band signals, then both stations change to communicate with the second codec. The second codec has compatible packet sizes of the deployed (originally negotiated) codec without any need of infrastructure upgrade and/or quality compromise to legacy phone users (i.e., stations that cannot operate with the second codec).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under the benefit of 35 U.S.C. §120 toProvisional Patent Application No. 61/348,203, filed on May 25, 2010,and Provisional Patent Application No. 61/373,243, filed on Aug. 12,2010. These provisional patent applications are hereby expresslyincorporated by reference herein in their entirety.

BACKGROUND

In telecommunications networks, information is transferred in an encodedform between a transmitting communication device and a receivingcommunication device, such as an originating station and a terminatingstation. The transmitting communication device encodes originalinformation, such as voice signals, into encoded information and sendsit to the receiving communication device. The receiving communicationdevice decodes the received encoded information to recreate the originalinformation. The encoding and decoding is performed using codecs. Theencoding of voice signals is performed in a codec located in thetransmitting communication device, and the decoding is performed in acodec located in the receiving communication device.

There are many different speech codecs. With some codecs, transcodingmay be required when the source and destination devices use incompatiblecodecs. Transcoding is a process by which a voice signal encodedaccording to one rate and encoding standard is converted to anotherencoding standard and possibly another rate. Transcoding can introducelatency and degradation in the voice signal being transmitted. To avoidthe difficulties associated with transcoding, transcoder-free operation(TrFO) has been developed. With transcoder-free operation, a connectionis established between telecommunications endpoints, such as mobiletelephones and/or non-mobile telephones, that have compatible codecs sothe connection does not use transcoders. TrFO has been widely deployedto eliminate the quality degradation due to network transcoding.Transcoding is not limited to the case when the source and thedestination device use incompatible codecs. Additionally, tandem freeoperation (TFO) is a technique that may be used to deliver encodedinformation from one device to another device faithfully when the corenetwork is circuit-switched.

Some telecommunications endpoints allow users to make calls over theInternet. Voice over Internet Protocol (VoIP) uses communicationprotocols and transmission technologies for delivery of voicecommunications and multimedia sessions over Internet Protocol (IP)networks, such as the Internet. VoIP systems use session controlprotocols to control the set up and ending of calls, and use audiocodecs which encode speech allowing transmission over an IP network asdigital audio via an audio stream. Codec use is varied between differentimplementations of VoIP. Often a range of codecs are used. Someimplementations use narrowband and compressed speech, while otherssupport high fidelity stereo codecs. VoIP systems do not use TFO or TrFOand may not perform transcoding.

Some codecs may not be implemented, however, because of infrastructureupgrade cost to operators and service providers as well as the corearchitectural complexity and availability of appropriate handsets. Forexample, Enhanced Variable Rate Wideband Codec (also referred to asEVRC-WB), developed with the latest speech compress technology, is ableto carry speech characteristics from 50 Hz to 7 kHz and thereforeprovides clearer and more natural sounds than any of its predecessors inthe EVRC (Enhanced Variable Rate Codec) family of codecs, like EVRC andEVRC-B which convey speech contents from 300 Hz to 4 kHz, that have beenoperated in cdma2000 networks. However, cdma2000 operators have notintroduced it due to a lack of understanding of the infrastructureupgrade cost and the hardware modifications that would be required forhandsets.

SUMMARY

After a call is established between two stations (such as two mobiledevices, two non-mobile devices, or one mobile device and one non-mobiledevice) using a codec that has been negotiated during call setup,in-band signaling may be used between the two stations to change thecodec that is resident in the mobile device or the end terminal to beused. The in-band signals are indicative that the station that istransmitting the in-band signals can operate with a second codec and areused to probe whether the receiving station can also operate with thatsecond codec. If the receiving station detects and reacts to the in-bandsignals, then both stations change to communicate with the second codec.The second codec has compatible packet sizes of the deployed (originallynegotiated) codec without any need of infrastructure upgrade and/orquality compromise to legacy phone users (i.e., stations that cannotoperate with the second codec).

In an implementation, the call is established with a first codec (e.g.,EVRC-B, narrowband), and in-band signals are sent from the terminatingstation to the originating station. The in-band signals are indicativethat the terminating station can operate with a second codec (e.g.,EVRC-WB, wideband) and are used to probe whether the originating stationcan also operate with the second codec. In some implementations, eitherstation or both stations can send the in-band signals after the call isestablished.

In an implementation, the in-band signals are designed such that (a)they are not received as a valid packet by a legacy decoder (e.g., adecoder that only operates in the first codec mode, or a decoder thatdoes not operate in the codec mode indicated by the in-band signalstransmitted by the terminating station), and (b) if they reach thereceiver of a station that can operate in the second codec mode, thestation can reliably conclude that the transmission path is transcodingfree and the station on the other side is also operable in the secondcodec mode so that it may switch to use the second codec.

In an implementation, the in-band signals are transmitted periodicallyfor a limited time frame to minimize the quality impact to legacy phoneusers.

In an implementation, during the communication between the stationsusing the second codec, it may be determined if an event occurs thatindicates that the first codec (the originally negotiated codec) shouldbe used instead of the second codec. Such an event may be a transcodingevent, a service option change, a three-way call, a conference call, ora handoff to a non-TrFO and/or non-TFO network. If such an event occurs,then the stations switch back to using the originally negotiated codec.In-band signals may also be used in a process of switching from thesecond codec to the first codec or a newly negotiated codec. Forexample, in an implementation, a call may be established between twostations, and the two stations may negotiate a first codec to use, suchas EVRC-B. At some point, the two stations switch to using a secondcodec, such as EVRC-WB. During the call, it is determined to include athird station on the call (e.g., make the call a three-way call with athird station). To include the third station, the two stations fallbackto using the first codec. At some point, the three-way call isterminated (the third station terminates being on the call), and the twostations switch back to using the second codec.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofillustrative embodiments, is better understood when read in conjunctionwith the appended drawings. For the purpose of illustrating theembodiments, there are shown in the drawings example constructions ofthe embodiments; however, the embodiments are not limited to thespecific methods and instrumentalities disclosed. In the drawings:

FIG. 1 is an illustration of an example environment for providing codecdeployment using in-band signals;

FIG. 2 is a diagram of an example network infrastructure;

FIG. 3 is a diagram of another example network infrastructure;

FIG. 4 is an illustration of another example environment for providingcodec deployment using in-band signals;

FIG. 5 is an operational flow of an implementation of a method forproviding codec deployment using in-band signals;

FIG. 6 is an operational flow of an implementation of a method forswitching from a first codec to a second codec with respect to aterminating station;

FIG. 7 is an operational flow of an implementation of a method forswitching from a first codec to a second codec with respect to anoriginating station;

FIG. 8 is an operational flow of another implementation of a method forproviding codec deployment using in-band signals;

FIG. 9 is an operational flow of an implementation of a method forswitching between codecs with respect to an originating station or aterminating station;

FIG. 10 is an operational flow of another implementation of a method forproviding codec deployment using in-band signals;

FIG. 11 is a diagram of an example mobile station; and

FIG. 12 shows an exemplary computing environment.

DETAILED DESCRIPTION

FIG. 1 is an illustration of an example environment 100 for providingcodec deployment using in-band signals. The environment 100 can use,without limitation, code division multiple access (CDMA) principles,Global System for Mobile Communications (GSM) principles, or otherwireless principles including wideband CDMA (WCDMA), cdma2000 (such ascdma2000 1× or 3× air interface standards, for example), time divisionmultiple access (TDMA), and frequency division multiple access (FDMA),for example. Multimedia content, including speech, can alternatively beprovided, for example, over a bidirectional point-to-point link ifdesired, such as, e.g., a Bluetooth link or a 802.11 link or a CDMA linkor GSM link. Likewise, speech content may also be transmitted using aVoice over Internet Protocol (VoIP). VoIP is a protocol optimized forthe transmission of voice through the Internet or other packet switchednetworks, which may interface with and/or merge with CDMA and GSM basedsystems.

Within the environment 100, a call is established between a mobilestation 110 and a mobile station 180 via base stations 120, 170, and anetwork 150. The base station 120 may establish a communication linkwith the mobile station 110 over the air interface. Various over the airinterfaces developed for wireless communication systems include FDMA,TDMA, and CDMA. In connection therewith, various domestic andinternational standards have been established including, e.g., AdvancedMobile Phone Service (AMPS), GSM, and Interim Standard 95 (IS-95).Implementations described herein reside in a wireless telephonycommunication system configured to employ a CDMA over the air interface.Nevertheless, it would be understood by those skilled in the art thatmethods and apparatuses having features as described herein may residein any of the various communication systems employing a wide range oftechnologies known to those of skill in the art, such as systemsemploying VoIP over wired and/or wireless (e.g., CDMA, TDMA, FDMA, etc.)transmission channels.

The base station 120 may establish a communication link with the basestation 170 through the network 150, and the base station 170 mayestablish a communication link with the mobile station 180 over the airinterface. The communication links may be CDMA communication links, butthe application is not limited thereto, as any wireless or wireline typecommunication links may be used depending on the implementation andwithout departing from the spirit of the invention.

In an implementation, the environment 100 may comprise a wirelesscommunication network. The wireless communication network may be a CDMAsystem, a GSM system, etc. Wireless communication networks are widelydeployed to provide various communication services such as voice, video,packet data, messaging, broadcast, etc. These wireless communicationnetworks may include packet switched networks and circuit switchednetworks. Packet switched refers to transfer of data for a user viacommon resources (e.g., a shared channel) that may be shared by multipleusers. Circuit switched refers to transfer of data for a user viadedicated resources (e.g., a dedicated channel) assigned to the user.Any network may be used within the environment 100, such as thosecapable of transcoder free operation (TrFO) or tandem free operation(TFO). Example networks include a cdma2000 1× circuit switched networkand a cdma2000 1× packet switched network, implementations of which aredescribed with respect to FIGS. 2 and 3, respectively, for example.

In an implementation, the network 150 (i.e., the core network),comprises a wired connection (e.g., a T1 or E1 type backhaul). A corenetwork is the well known central part of a telecommunications networkthat provides various services to customers who are connected to it,e.g. by an access network. In some implementations, the core network(e.g., the network 150) may be wireless. Depending on theimplementation, the connection between the base station(s) 120, 170 andthe core network may be wired or wireless.

The techniques described herein may be used for the networks andtechnologies mentioned above as well as other networks and radiotechnologies. For clarity, certain aspects of the techniques aredescribed below for 3GPP2 networks, and 3GPP2 terminology is used inmuch of the description below. In 3GPP2, IS-2000 Releases 0 and A arecommonly referred to as cdma2000 1×, and IS-2000 Release C is commonlyreferred to as cdma2000 1×EV-DV. IS-2000 networks are circuit switchednetworks and are commonly referred to as 1× networks. IS-856 is commonlyreferred to as High Rate Packet Data (HRPD), cdma2000 1×EV-DO, 1×EV-DO,1×-DO, DO, High Data Rate (HDR), etc. IS-856 networks are packetswitched networks and are commonly referred to as HRPD networks.

Each mobile station 110, 180 may be a wireless communication device suchas a cellular phone, a terminal, a handset, a personal digital assistant(PDA), a wireless modem, a cordless phone, a handheld device, a laptopcomputer, etc. An example mobile station is described with respect toFIG. 11.

The mobile station 110 has a codec set 112 and the mobile station 180has a codec set 182. Each codec set 112, 182 has a number of codecs thatcan be selectively enabled for processing audio data. The codec set 112may be the same or different as the codec set 182. For example, thecodec set 112 may have the same number of codecs and the samecapabilities as the codec set 182. As another example, the codec set 112may have a different number of codecs and/or different capabilities asthe codec set 182. Examples of codecs that can be included in the codecsets 112, 182 include EVRC-WB and EVRC-B, although any number and typesof codecs can be used without departing from the spirit of theinvention.

The mobile station 110 may also comprise an in-band signal processor114, an in-band signal transmitter 116, and an in-band signal receiver118. The in-band signal processor 114 may generate in-band signals fortransmission from the in-band signal transmitter 116 to the mobilestation 180, and may process in-band signals received via the in-bandsignal receiver 118 from the mobile station 180. Similarly, the mobilestation 180 may comprise an in-band signal processor 184 to generatein-band signals for transmission from an in-band signal transmitter 186to the mobile station 110, and to process in-band signals received viathe in-band signal receiver 188 from the mobile station 110. Intelecommunications, in-band signaling is the sending of metadata andcontrol information in the same band, on the same channel, as used fordata; that is, utilizing the connection reserved for user datatransmission.

Call setup is the process of establishing dedicated physical channelsand negotiating service configuration parameters between a mobilestation and a base station so that communication can take place. After acall is established between the two mobile stations 110 and 180 using acodec that has been negotiated during call setup, in-band signaling maybe used between the two mobile stations 110, 180 to change the codecthat is to be used.

In an implementation, the call is established with a first codec (e.g.,EVRC-B, narrowband), and in-band signals are sent from the terminating(i.e., receiving) station to the originating mobile station. The in-bandsignals are indicative that the terminating station can operate with asecond codec (e.g., EVRC-WB, wideband) and are used to probe whether theoriginating station can also operate with the second codec. If theoriginating station detects and reacts to the in-band signals, then bothstations communicate with the second codec. The second codec enhancesuser call experience and has compatible packet sizes of the deployed(first) codec without any need of infrastructure upgrade and/or qualitycompromise to legacy phone users (i.e., stations that cannot operatewith the second codec). Thus, in an implementation, in-band signaling isused to determine the capabilities of the stations and/or to set thecodec mode to wideband or narrowband. The switching between the codecmodes is not visible to the infrastructure.

In an implementation, the in-band signals are designed such that (a)they are not received as a valid packet by a legacy decoder (e.g., adecoder that only operates in the first codec mode, such as a EVRC-Bdecoder, or a decoder that does not operate in the codec mode indicatedby the in-band signals transmitted by the terminating station) and (b)if they reach the receiver of a station that can operate in the secondcodec mode, the station can reliably conclude that (1) the transmissionpath is transcoding free and (2) the station on the other side is alsooperable in the second codec mode so that it will switch (or be ready toswitch) to use the second codec. The in-band signals are transmittedperiodically for a limited time frame to minimize the quality impact tolegacy phone users.

The call may be established in a packet switched network, such ascdma2000 1×. A transcoder-free operation (TrFO) call may transit to anon-TrFO call in various scenarios, like when a third party joins in themiddle of the call (three-party calling) or when call waiting or callforwarding is initiated. In an implementation, the mobile stations areequipped with the means (e.g., through call processing messages) todetect the network transition from TrFO to non-TrFO during a call andswitch back to using the first codec (e.g., EVRC-B, narrowband).

Each mobile station may be capable of communicating with packet switchednetworks and circuit switched networks. It is contemplated and herebydisclosed that the configurations disclosed herein may be adapted foruse in networks that are packet switched (for example, wired and/orwireless networks arranged to carry audio transmissions according toprotocols such as VoIP) and/or circuit switched. It is also contemplatedand hereby disclosed that the configurations disclosed herein may beadapted for use in narrowband coding systems (e.g., systems that encodean audio frequency range of about four or five kilohertz) and for use inwideband coding systems (e.g., systems that encode audio frequenciesgreater than five kilohertz), including whole-band wideband codingsystems and split-band wideband coding systems. Example combinationsinclude circuit switched air interface and circuit switched corenetwork, circuit switched air interface and packet switched corenetwork, and IP access and packet switched core network, for example.

FIG. 2 is a diagram of an example circuit switched network 200. Thenetwork 200 comprises mobile stations 205, 230 (MS1, MS2), base stations210, 225 (BS1, BS2), mobile switching centers 215, 220 (MSC1, MSC2), apublic switched telephone network 235 (PSTN), and a fixed phone 240. TheMSCs 215, 220 may support circuit switched services (e.g., voice) andmay perform radio resource management, mobility management, and otherfunctions to support communications for the mobile stations 205, 230with circuit switched calls. It is contemplated that wideband servicemay be used for a mobile to mobile call in an implementation if thenetwork can operate in TFO.

Modern Second Generation (2G) and Third Generation (3G) radio telephonecommunication systems have sought to produce voice quality commensuratewith the conventional PSTN. The PSTN has traditionally been limited inbandwidth to the frequency range of 300-3400 kHz. New networks for voicecommunications, such as cellular telephony and VoIP, are not necessarilyconstrained by the same bandwidth limits. Accordingly, it may bedesirable to transmit and receive voice communications that include awideband frequency range over such networks. For example, it may bedesirable to support an audio frequency range that extends down to 50 Hzand/or up to 7 or 8 kHz. It may also be desirable to support otherapplications, such as high-quality audio or audio/video conferencing,that may have audio speech content in ranges outside the traditionalPSTN limits. Codecs which seek to extend the audio frequency range asset forth above are commonly referred to as wideband codecs.

FIG. 3 is a diagram of an example packet switched network 300. Thenetwork 300 comprises mobile stations 305, 330 (MS1, MS2), base stations310, 325 (BS1, BS2), mobile switching center emulations 340, 345 (MSCe1,MSCe2), and media gateways 315, 320 (MGW1, MGW2). The MGWs 315, 320 maybe translation devices or services that convert digital media streamsbetween disparate telecommunications networks such as PSTN, SS7, NextGeneration Networks (2G, 2.5G and 3G radio access networks) or PBX.Media gateways enable multimedia communications across Next GenerationNetworks over multiple transport protocols such as Asynchronous TransferMode (ATM) and Internet Protocol (IP). The MGWs 315, 320 may convertbetween different transmission and coding techniques. Media streamingfunctions such as echo cancellation, DTMF, and tone sender are alsolocated in the media gateway. The MSCes 340, 345 may emulate a mobileswitching center (MSC) for call processing.

Circuit switched networks and packet switched networks are well knownand a further description is omitted for brevity. The networks 200 and300 are not limited to the components shown and may comprise more orfewer mobile stations, base stations, mobile switching centers, mobileswitching center emulations, media gateways, and fixed phones, forexample, and may comprise alternative and/or additional components notshown.

The collection of base stations, mobile switching centers, mobileswitching center emulations, and media gateways, if any, may be referredto as “infrastructure”. To enable a new codec, conventionally theinfrastructure of the network needs substantial changes to ensureinterworking and interoperability. Conventionally, to enable EVRC-WB,for example, other than the enhancement of the mobile station, almostall of the entities of the network infrastructure, including the basestation, the mobile switching center or mobile switching centeremulation and media gateway and the signaling and protocols between theinterfaces are required to be upgraded.

However, in an implementation, if the network operates intranscoder-free operation (TrFO), i.e., the audio packets are able to bedelivered from one end to the other unaltered, and the end usersinvolved in the conversation are able to have EVRC-WB quality if both ofthem are using mobile stations as described herein, without anyinfrastructure upgrade. A TrFO system over cdma2000 1× may beimplemented using the network shown in FIG. 3, for example. A TrFO callmay transit to a non-TrFO call in various scenarios, such as when athird party joins in the middle of the call. As described herein, astation is able to immediately detect such events and switch back to usea negotiated codec (i.e., the codec used in the completion of the callsetup) before the onset of such event.

In an implementation, a call is established between a first mobilestation and a second mobile station. It is determined if both mobilestations are “special” as defined herein. If so, a wideband mode isentered into, and otherwise a narrowband mode is entered into. Asdescribed further herein, in-band signaling may be used along withprobes and/or protocols in order to determine the capabilities of themobile stations (e.g., whether one or more of the mobile stations isspecial) and/or to set a particular codec mode (e.g., wideband ornarrowband). The switching between the modes is not visible to theinfrastructure. Thus, the infrastructure continues to operate as if in afirst mode (e.g., previously negotiated or deployed mode, such asnarrowband) even when the mode has been set to wideband or to anotherenhanced mode.

More particularly, end-to-end in-band signaling is used to deploy orotherwise enable a codec which enhances user call experience and hascompatible packet sizes of the deployed negotiated codec without anyneed of infrastructure upgrade and/or quality compromise to legacy phoneusers (i.e., users of mobile stations or non-mobile stations that do nothave the in-band signaling functionality described herein and thus arenot “special”).

In-band signaling may also be used to determine, acquire, or send theoperation status of the network (e.g., whether it is TrFO or non-TrFOoperation). Identifiers may be used to indicate the operation status.

In an implementation, the infrastructure may comprise VoIP components sothat one or both stations of the call are VoIP clients. For example, amobile station may communicate with a VoIP station via an infrastructurecomprising a base station and a MSC (or MSCe and MGW) as set forth abovein communication with a VoIP gateway via an IP cloud. The VoIP gatewaymay communicate with the VoIP client. In this manner, a mobile stationmay communicate with a VoIP station which may be non-mobile. The in-bandsignaling techniques set forth herein may be used to deploy a codec forthe mobile station and the VoIP station to use for a call that has beensetup between the two stations.

FIG. 4 is an illustration of another example environment 400 forproviding codec deployment using in-band signals. Endpoint 410 andendpoint 480 (also referred to as stations) are communication devicesthat communicate with each other via a network 450. Each endpoint 410,480 may be a mobile station as described above for example (e.g.,running circuit switched voice or VoIP), or may be a non-mobile stationsuch as a personal computer (PC) or a telephone for example. In otherwords, each endpoint 410, 480 can be any terminal or computing deviceadapted for communication with another endpoint over the network 450. Anexample computing device that may comprise a non-mobile station, forexample, is described with respect to FIG. 12.

Each endpoint 410, 480 comprises a codec set 412, 482, an in-band signalprocessor 414, 484, an in-band signal transmitter 416, 486, and anin-band signal receiver 418, 488, similar to that described with respectto FIG. 1. As described further herein, each codec set 412, 482 has anumber of codecs that can be selectively enabled for processing audiodata, and the codec set 412 may be the same or different as the codecset 482. Any number and types of codecs can be used without departingfrom the spirit of the invention.

Similar to the functionality described with respect to FIG. 1, forexample, each in-band signal processor (e.g., processor 414) maygenerate in-band signals for transmission from the in-band signaltransmitter (e.g., transmitter 416) to the other endpoint (e.g.,endpoint 480) via the network 450, and may process in-band signalsreceived via the in-band signal receiver (e.g., receiver 418) from theother endpoint. Each in-band signal processor, in-band signaltransmitter, and in-band signal receiver may be implemented using one ormore computing devices such as the computing device 1200 illustrated inFIG. 12.

As described further herein, after a call is established between the twoendpoints 410, 480 using a codec that has been negotiated during callsetup, in-band signaling may be used between the two endpoints 410, 480to change the codec that is to be used. In an implementation, the callis established with a first codec and in-band probe signals are sentfrom the terminating endpoint to the originating endpoint to probewhether the originating endpoint can also operate with the second codec.If the originating endpoint detects and reacts to the in-band signals,then both endpoints communicate with the second codec. There is no needof infrastructure upgrade and/or quality compromise to users ofendpoints that cannot operate with the second codec. Thus, in animplementation, in-band signaling is used to determine the capabilitiesof the endpoint and/or to set the codec mode. The switching between thecodec modes is not visible to the infrastructure.

The network 450 can be any network, depending on the implementation. Thenetwork 450 may comprise any combination of the access and core network,and the access network of endpoint 410 can be different from that ofendpoint 480. For example, the access network can be 1×, DO, UMTS, DSL,etc. The core network could be circuit switched domain, packet switcheddomain, IP, etc.

The in-band signaling techniques allow an endpoint to determine if theother endpoint also has the in-band signaling solution (i.e., is specialas described herein) and if the network delivers packets end-to-endwithout alternation and so that codec deployment and/or switching usingthe techniques herein is possible. Although the techniques describedherein do not need to be aware of the actual network, some knowledge ofthe network may be beneficial depending on the implementation. Forexample, for a 1× access network, if the endpoint knows ahead that athree-way call will happen by examining L3 signaling, it can initiate atransition from one codec to another codec (e.g., from EVRC-WB toEVRC-B) ahead of time, rather than rely on received speech packets, sothat the transition is more smooth and the user experience is better.

FIG. 5 is an operational flow of an implementation of a method 400 forproviding codec deployment using in-band signals. At 510, a call setupis completed between two stations (also referred to as endpoints), suchas mobile station 110 and mobile station 180 or endpoint 410 andendpoint 480. For example, mobile station 110 may be the originatingstation and mobile station 180 may be the terminating station, orendpoint 410 may be the originating station and endpoint 480 may be theterminating station. Each station may be a mobile device or a non-mobiledevice.

Upon call setup, the originating station and the terminating stationcommunicate at 520 using a previously negotiated codec, referred to as afirst codec, such as a narrowband codec. The previously negotiated codecmay be a predetermined codec that is to be used by stations on thenetwork. Any station on the network may use the previously negotiatedcodec, including legacy stations which are stations that are notequipped with the in-band signaling functionality and features describedherein.

At 530, the terminating station (if it is a special station with in-bandsignaling functionality) generates in-band signals and sends the in-bandsignals as a probe to the originating station. The in-band signals areindicative that the terminating station can operate with a second codec(e.g., wideband) and are used to probe whether the originating stationcan also operate with the second codec. The in-band signals may be usedto determine whether the network operates in a non-transcoding mode, inan implementation. The in-band signals may be sent when speech isdetected or when the terminating station picks up, for example. Thus,the in-band signaling is only sent after the call has been established.In an implementation, the terminating station starts a timer when itbegins sending the in-band probe signals. The timer may be used todetermine the length of time that the terminating station sends thein-band probe signals. The terminating station may stop transmitting thein-band probe signals after a predetermined length of time if there hasbeen no response from the originating station.

At 540, it is determined at the terminating station whether theoriginating station has detected and reacted to the in-band signals sentby the terminating station. It may be determined that the originatingstation has detected and reacted to the in-band signals if theoriginating station generates and sends a response using in-bandsignaling to the terminating station.

At 550, if the originating station fails to respond to the in-band probesignals sent by the terminating station (e.g., within the predeterminedamount of time as measured by the timer), then communication between thetwo stations continues using the originally negotiated codec. In thismanner, because the originating station did not react to the in-bandprobe signals, the originating station is not considered to have thecapability to operate in the second codec. This may happen, for example,if the network does not operate in a non-transcoding mode, and/or if theoriginating station is not a special station. Thus, users of legacystations may still call and communicate with stations that can operatewith the second codec (special stations).

At 560, if the originating station does detect and respond to thein-band probe signals, e.g. by sending a confirmation signal to theterminating station, then the stations switch to communicate using thesecond codec without any change or modification to the infrastructure.The second codec enhances user call experience and has compatible packetsizes of the deployed (first) codec without any need of infrastructureupgrade. The switching between codec modes and the use of the secondcodec mode is not visible to the infrastructure. Thus, theinfrastructure remains running in the first codec mode. Communicationproceeds using the second codec until the call terminates or until anevent occurs that indicates that the first codec (or another codec suchas a newly negotiated codec) should be used instead of the second codec,as described further with respect to FIGS. 8 and 9, for example. Thus,in-band signaling is used to determine the capabilities of the stationsand/or to set the codec mode, e.g. to wideband or narrowband.

In an implementation, to be able to run EVRC-WB on EVRC-B, TrFO is inplace. The protocol and signals, described herein, achieve the switchfrom EVRC-B to EVRC-WB upon completion of call setup and switch back toEVRC-B when TrFO is broken. EVRC-B and SO 68 (service option 68) areused interchangeably herein, as are EVRC-WB and SO 70 (service option70).

In an implementation, a special station is capable of supporting bothEVRC-B (SO 68) and EVRC-WB (SO 70), and generating, detecting, andreacting to special in-band signals, including a probe signal, anacknowledgement to probe signal, a change to wideband signal and achange to narrowband signal, for example, and performing additionaloperations before responding to some of the Layer 3 messages.

Take enabling EVRC-WB on EVRC-B over cdma2000 1× as an example. FIGS. 6and 7 illustrate the procedures of terminating and originating stationsimmediately after call setup. FIG. 6 is an operational flow of animplementation of a method 600 for switching from a first codec, such asEVRC-B, to a second codec, such as EVRC-WB, with respect to aterminating station. FIG. 7 is an operational flow of an implementationof a method 700 for switching from the first codec to the second codecwith respect to an originating station.

FIG. 6 provides an example terminating station procedure after callsetup, assuming the terminating station is a special station. At 610, acall setup is considered complete after two stations negotiate a calland the call is setup. After the call setup is complete at 610, it maybe determined at 620 if the terminating station is transmitting with aparticular predetermined service codec, such as EVRC-B SO68 COP0(corresponding to narrowband, operating at capacity operating point 0),for example. SO68 defines a particular codec (e.g., narrowband), andCOP0 defines an average rate that it is targeting. COP0 may be apre-requisite in some implementations because the average data rate ofCOP0 is greater than or equal to that of EVRC-WB COP0 (the widebandmode). Any of the other COPs of EVRC-B has an average data rate lessthan that of EVRC-WB, so if EVRC-B COP4 is switched to EVRC-WB, forexample, channel capacity might be negatively impacted. In animplementation, the station provides a list of supported codes it cansupport to the base station. The base station then tells the stationwhich codec to use. If the predetermined codec is not being used, andanother codec is, then communication continues at 645 using the codecthat was originally negotiated.

However, if the terminating station is special, and if the negotiatedservice codec is the predetermined service codec (e.g., EVRC-B SO68COP0) as determined at 620, then the terminating station starts sendingan in-band probe signal periodically and sets a timer at 630. In animplementation, the in-band signal is sent once every 16 frames, forexample. The in-band signal that is sent from the terminating station tothe originating station indicates that the terminating station isspecial. The in-band signal is only sent for an amount of time set bythe timer (e.g., 20 seconds). When the timer expires, the terminatingstation stops sending the in-band signal.

Thus, in an implementation, the terminating station immediately afterthe completion of call setup, starts sending a probe signal once everypredetermined number of frames and sets a timer, if the terminatingstation is special and the negotiated service option meets thepredetermined criteria. The probe signal is transmitted in-band. Forexample, each time a probe needs to be transmitted, if the normal frameis full rate or eighth rate, a full rate probe is used to replace thenormal frame, and if the normal frame is a half rate, a half rate probeis used to replace the normal frame.

Before the timer expires, at 640, if the terminating station receives anacknowledgement which indicates the originating station is also specialand that the originating station has reliably detected the probe signal,it sends a change to wideband mode signal and enters normal EVRC-WBoperation at 650 (e.g., it switches its speech encoder to EVRC-WB andsends wideband full rate packets). The acknowledgement may be anindication that comprises a special signal, an in-band signal, or asequence of wideband frames based on packet structure, for example(e.g., no quarter rate structure). Otherwise, either the originatingstation is a legacy station or the probe signal is not reliably detectedby the originating station in time before the timer expires; thus, eventhough the terminating station is a special phone, at 645, theterminating station remains in the original codec mode until callrelease.

Turning to FIG. 7, after call setup is complete at 710, it is determinedat 720 if the originating station is special, and if the negotiatedservice codec is a predetermined service codec (e.g., SO 68 COP 0), forexample. If the predetermined codec is not being used, and another codecis, then communication continues at 745 using the codec that wasoriginally negotiated. In such a case, the receiver of the originatingstation does not need to detect the probe and just treats the probe asan erasure, as in a normal decoding process. Otherwise, the receivershall enable the probe detection procedure while monitoring the receivedframe type.

If the negotiated service codec is determined at 720 to be the properpredetermined service codec, it may be determined at 730 whether itsreceiver successfully detects a number m of in-band probe signals, wherem may be any predetermined integer, such as 1 or 2, for example. If so,then the originating station sends an acknowledgement of the widebandmode to the terminating station and switches its speech encoder to thewideband mode (e.g., EVRC-WB) and starts sending wideband full ratepackets, at 740. Otherwise, the originating station continuestransmitting in the negotiated codec mode at 745. Thus, if theoriginating station is a legacy station, then its receiver processes thereceived packets as usual. Each probe is treated as an erasure as the“delay index” field does not contain a valid value.

Thus, if m probes are received (which implies this is a TrFO scenarioand the terminating station is special), then the originating stationsends an acknowledgement signal and enters the EVRC-WB mode at 740.

As noted above, probe signaling is transmitted by the terminatingstation right after call setup, if it is a special phone. In animplementation, the probe signaling is either a full rate (171 bits) ora half rate (40 bits) frame carrying a unique message.

The acknowledgement probe signaling is transmitted by the originatingstation after it detects probe signaling, if it is a special phone. Theacknowledgement probe signaling may comprise consecutive EVRC-WB fullrate frames, for example.

The change to wideband signaling is transmitted by the terminatingstation after it detects the acknowledgement probe signaling receivedfrom the originating station. The change to wideband signaling maycomprise consecutive EVRC-WB full rate frames.

In an implementation, the change to narrowband signaling is transmittedby either the terminating station or the originating station when it isin EVRC-WB mode and detects any trigger indicating that transcoding freeoperation is going to be broken, as described further below with respectto FIGS. 8 and 9. The change to narrowband signaling could be anacknowledgement to probe signaling consisting of consecutive EVRC-B fullrate frames or some other signaling carrying some special messages thatcan be reliably detected by a special station.

FIG. 8 is an operational flow of another implementation of a method 800for providing codec deployment using end-to-end signals and protocols.At 810 and 820, similar to 510 and 520, a call setup is completedbetween two stations, and the originating station and the terminatingstation communicate using a previously negotiated codec.

At 830, similar to 530, the terminating station generates in-bandsignals and sends the in-band signals as a probe to the originatingstation for a predetermined amount of time or until the originatingstation responds. At 840, the originating station detects and reacts tothe in-band signals sent by the terminating station. The stations switchto communicate using the second codec, without any change to the networkinfrastructure.

Continuously during the communication between the stations using thesecond codec, at 850, it may be determined if an event occurs thatindicates that the first codec (originally negotiated codec) should beused instead of the second codec. Such an event may be a transcodingevent, a service option change, or a handoff to a non-TrFO network, forexample.

If such an event occurs, then the stations switch back to using theoriginally negotiated codec at 870. Otherwise, communication continuesbetween the two stations at 860 using the second codec.

In an implementation where the call is switched from EVRC-B to EVRC-WBand before the call is released, both the terminating station and theoriginating station monitor the received traffic and the Layer 3 signal.The Layer 3 signal is transmitted to sense any sign that TrFO might beabout to be broken or is broken. One sign that TrFO is possibly brokenis that a narrowband frame (e.g., quarter rate frame, full rate framewith the last bit being ‘0’, eighth rate frame with the last bit being‘0’, special half rate frame, etc.) is received. In this case, eitherone of the stations initiates the switch from EVRC-WB to EVRC-B or atleast one of the stations is handed off to a network that does notsupport TrFO. Therefore, transcoding begins, the speech encodertransmits a change to narrowband signal immediately, followed by sendingnormal EVRC-B packets, and the audio output is muted for a predeterminednumber of frames before it processes the received frame in normalnarrowband mode. If the receiver can reliably detect a change tonarrowband signal, it can immediately process the received frame innormal narrowband mode without audio output muting.

Additional indications that TrFO is about to be broken include receivinga service negotiation message (including Service Connect Message,Service Option Control Message, Service Request Message, ServiceResponse Message, General Handoff Direction Message, and UniversalHandoff Direction Message, for example) or a service option negotiationmessage (including Service Option Request Order, Service Option ResponseOrder, and Service Option Control Order, for example) which requiresvocoder change and/or COP change, an alert or flash with informationmessage (e.g., call waiting tone). In addition to an alert withinformation message, flash with information message, or handoff message,the alert, flash, or handoff may be of the “extended” type (e.g., anextended alert, extended flash, or extended handoff in which the alert,flash, or handoff is an extended message). In these scenarios, thespeech encoder sends a change to narrowband signal, followed by normalEVRC-B process. Additionally, if one station detects its user wants toinitiate three-party calling or sending DTMF tones, it sends a change tonarrowband signal, possibly followed by normal EVRC-B process, beforesending flash with information message (dialed digits) or sending burstDTMF Message. An example procedure of a special station in EVRC-WB isshown with respect to FIG. 9.

FIG. 9 is an operational flow of an implementation of a method 900 forswitching between codecs, such as from EVRC-WB to EVRC-B, with respectto an originating station or a terminating station. FIG. 9 describesprocedures that two special stations follow in an implementation toswitch between two codecs.

At 910, the communication continues in wideband mode after having beenset to the wideband mode as described above for example, and it may bedetermined at 920 if the call is released. If not, at 930, it may bedetermined if a transcoding event occurs, such as call waiting occurs,third party adding, one of the stations moves to a non-TrFO network. Forexample, a few valid quarter rates may be received which indicates amove to a non-TrFO network. If so, then at 940, for the decoder, theaudio output is disabled for a predetermined amount of seconds (Xseconds, where X is >0 and predetermined) and reset, and for theencoder, a change to narrowband signal is sent to change it to thecorresponding narrowband mode until call release. Optionally, at 980,after a certain amount of time, the stations may try to switch back towideband mode again, e.g., using in-band signaling as described herein.

At 950, it may be determined if a handoff is detected or if a serviceoption change has been initiated, e.g., if a message is beingtransmitted or received that gives an indication that another party isbeing included in the call or a service option is changing, to indicatea handoff to a non-TrFO mode. If so, then at 960, the station sendschange to narrowband mode signals to the other station, and afterreceiving narrowband packets the station changes to the correspondingnarrowband mode until call release. Thus, the technique triggers back tonarrowband if a party using one of the stations initiates callforwarding, call waiting, or third party calling. Otherwise, processingmay continue at 910.

In an implementation, if a station wants to initiate three-partycalling, it switches its speech encoder to EVRC-B, sends full ratepackets until its speech decoder switches to narrowband, starts sendingnormal EVRC-B packets, and then sends flash with information message(dialed digits). Similarly, before a station sends a send burst DTMFmessage, it switches its speech encoder to EVRC-B, sends full ratepackets until its speech decoder switches to narrowband, starts sendingnormal EVRC-B packets, and then sends a send burst DTMF message. If astation receives an alert or flash with information message (callwaiting tone), it switches its speech encoder to EVRC-B, sends full ratepackets until its speech decoder switches to narrowband, starts sendingnormal EVRC-B packets and proceeds with the subsequent operations afterreceiving the alert or flash with information message.

If a station receives a predetermined number of consecutive narrowbandframes (including full rate frame with 171st bit=0, eighth rate framewith 16th bit=0, quarter rate frame, and half rate frame following anytype of these frames), the speech decoder considers the narrowbandframes (starting from the second narrowband frame) as erased frames, andthe encoder switches to EVRC-B and sends change to narrowband signalsbefore sending normal EVRC-B packets. In an implementation, during thetransmission of change to wideband signals, change to narrowbandsignals, or acknowledge probe signals, the station may use forwardtraffic channel supervision to adjust its transmission durationaccordingly.

In an implementation directed to third party adding (an example of atranscoding event), a call may be established between two stations, andthe two stations may negotiate a first codec to use, such as EVRC-B. Atsome point, the two stations switch to using a second codec, such asEVRC-WB (e.g., at 910). During the call, it is determined to include athird station on the call (e.g., make the call a three-way call with athird station) (e.g., at 930). To include the third station, the twostations fallback to using the first codec (e.g., at 940). At somepoint, the three-way call is terminated (the third station terminatesbeing on the call), and the two stations switch back to using the secondcodec.

Implementations described herein (e.g., with respect to the methods 500through 800) describe the terminating station sending the in-band probesignals to the originating station. However, alternatively oradditionally, the originating station may send the in-band probe signalsto the terminating station. In such implementations, the terminatingstation, if it is not a legacy station, may detect and respond to thein-band signals sent by the originating station.

In an implementation, one station may be equipped so that it sendsin-band probe signals regardless of whether it is the originatingstation or the terminating station. However, the station can communicatewith another station which only sends the in-band signal when it is theterminating station, such as for example when a PC client iscommunicating with a mobile device.

FIG. 10 is an operational flow of another implementation of a method 900for providing codec deployment using in-band signals. At 1010 and 1020,similar to 510 and 520, a call setup is completed between two stations,and the originating station and the terminating station communicateusing a previously negotiated codec.

At 1030, each station that is equipped with the in-band signalingcapability generates in-band signals and sends the in-band signals as aprobe to the other station. Depending on how each station is equipped(e.g., whether a station is a legacy station or a special station, asthe terms are used herein), each station may be equipped to send in-bandprobe signals and wait for a response from the other station, or onlyone of the stations may be equipped to send in-band probe signals andwait for (or monitor) a response from the other station. The in-bandsignals are indicative that the transmitting station can operate with asecond codec and are used to probe whether the other station can alsooperate with the second codec. In an implementation, each transmittingstation (i.e., each special station) starts a timer when it beginssending the in-band probe signals. The timer may be used to determinethe length of time that the transmitting station sends the in-band probesignals and the transmitting station may stop transmitting the in-bandprobe signals after a predetermined length of time if there has been noresponse from the other station. In an implementation, the probe may beused to determine whether or not transcoding is present on thetransmission path and/or whether the other station is also a specialstation.

At 1040, it is determined at the transmitting station whether the otherstation has detected and reacted to the in-band signals sent by thetransmitting station. It may be determined that the other station hasdetected and reacted to the in-band signals if it generates and sends aresponse using in-band signaling to the transmitting station. If bothstations are transmitting in-band signals, then it may be determined ifboth of the stations detect and react to the in-band signals.

At 1050, if neither of the stations (if both stations are acting astransmitting stations, although it is contemplated that only one of thestations acts as a transmitting station as described further herein)detect and react to the in-band signals sent by the other station (e.g.,within the predetermined amount of time as measured by the timer(s) setby the transmitting station(s)), then communication between the twostations continues using the originally negotiated codec. However, at1060, if the one of the stations does detect and respond to the in-bandprobe signals, e.g. by sending a confirmation signal to the transmittingstation, then the stations switch to communicate using the second codec.The switching between codec modes and the use of the second codec modeis not visible to the infrastructure. Communication proceeds using thesecond codec until the call terminates or until an event occurs thatindicates that the first codec (or a newly negotiated codec) should beused instead of the second codec, as described further herein.

It is contemplated that all of the in-band signaling functionalities ofthe stations (i.e., to make them “special”) can be achieved throughsoftware/firmware upgrade. The user experience is enhanced without anyinfrastructure upgrade and without negative impact to legacy phoneusers.

As used herein, the term “determining” (and grammatical variantsthereof) is used in an extremely broad sense. The term “determining”encompasses a wide variety of actions and, therefore, “determining” caninclude calculating, computing, processing, deriving, investigating,looking up (e.g., looking up in a table, a database or another datastructure), ascertaining and the like. Also, “determining” can includereceiving (e.g., receiving information), accessing (e.g., accessing datain a memory) and the like. Also, “determining” can include resolving,selecting, choosing, establishing and the like.

The term “signal processing” (and grammatical variants thereof) mayrefer to the processing and interpretation of signals. Signals ofinterest may include sound, images, and many others. Processing of suchsignals may include storage and reconstruction, separation ofinformation from noise, compression, and feature extraction. The term“digital signal processing” may refer to the study of signals in adigital representation and the processing methods of these signals.Digital signal processing is an element of many communicationstechnologies such as mobile stations, non-mobile stations, and theInternet. The algorithms that are utilized for digital signal processingmay be performed using specialized computers, which may make use ofspecialized microprocessors called digital signal processors (sometimesabbreviated as DSPs).

Unless indicated otherwise, any disclosure of an operation of anapparatus having a particular feature is also expressly intended todisclose a method having an analogous feature (and vice versa), and anydisclosure of an operation of an apparatus according to a particularconfiguration is also expressly intended to disclose a method accordingto an analogous configuration (and vice versa).

FIG. 11 shows a block diagram of a design of an example mobile station1100 in a wireless communication system. Mobile station 1100 may be acellular phone, a terminal, a handset, a PDA, a wireless modem, acordless phone, etc. The wireless communication system may be a CDMAsystem, a GSM system, etc.

Mobile station 1100 is capable of providing bidirectional communicationvia a receive path and a transmit path. On the receive path, signalstransmitted by base stations are received by an antenna 1112 andprovided to a receiver (RCVR) 1114. Receiver 1114 conditions anddigitizes the received signal and provides samples to a digital section1120 for further processing. On the transmit path, a transmitter (TMTR)1116 receives data to be transmitted from digital section 1120,processes and conditions the data, and generates a modulated signal,which is transmitted via antenna 1112 to the base stations. Receiver1114 and transmitter 1116 may be part of a transceiver that may supportCDMA, GSM, etc.

Digital section 1120 includes various processing, interface, and memoryunits such as, for example, a modem processor 1122, a reducedinstruction set computer/ digital signal processor (RISC/DSP) 1124, acontroller/processor 1126, an internal memory 1128, a generalized audioencoder 1132, a generalized audio decoder 1134, a graphics/displayprocessor 1136, and an external bus interface (EBI) 1138. Modemprocessor 1122 may perform processing for data transmission andreception, e.g., encoding, modulation, demodulation, and decoding.RISC/DSP 1124 may perform general and specialized processing forwireless device 1100. Controller/processor 1126 may direct the operationof various processing and interface units within digital section 1120.Internal memory 1128 may store data and/or instructions for variousunits within digital section 1120.

Generalized audio encoder 1132 may perform encoding for input signalsfrom an audio source 1142, a microphone 1143, etc. Generalized audiodecoder 1134 may perform decoding for coded audio data and may provideoutput signals to a speaker/headset 1144. Graphics/display processor1136 may perform processing for graphics, videos, images, and texts,which may be presented to a display unit 1146. EBI 1138 may facilitatetransfer of data between digital section 1120 and a main memory 1148.

Digital section 1120 may be implemented with one or more processors,DSPs, microprocessors, RISCs, etc. Digital section 1120 may also befabricated on one or more application specific integrated circuits(ASICs) and/or some other type of integrated circuits (ICs).

FIG. 12 shows an exemplary computing environment in which exampleimplementations and aspects may be implemented. The computing systemenvironment is only one example of a suitable computing environment andis not intended to suggest any limitation as to the scope of use orfunctionality.

Computer-executable instructions, such as program modules, beingexecuted by a computer may be used. Generally, program modules includeroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data types.Distributed computing environments may be used where tasks are performedby remote processing devices that are linked through a communicationsnetwork or other data transmission medium. In a distributed computingenvironment, program modules and other data may be located in both localand remote computer storage media including memory storage devices.

With reference to FIG. 12, an exemplary system for implementing aspectsdescribed herein includes a computing device, such as computing device1200. In its most basic configuration, computing device 1200 typicallyincludes at least one processing unit 1202 and memory 1204. Depending onthe exact configuration and type of computing device, memory 1204 may bevolatile (such as random access memory (RAM)), non-volatile (such asread-only memory (ROM), flash memory, etc.), or some combination of thetwo. This most basic configuration is illustrated in FIG. 12 by dashedline 1206.

Computing device 1200 may have additional features and/or functionality.For example, computing device 1200 may include additional storage(removable and/or non-removable) including, but not limited to, magneticor optical disks or tape. Such additional storage is illustrated in FIG.12 by removable storage 1208 and non-removable storage 1210.

Computing device 1200 typically includes a variety of computer-readablemedia. Computer-readable media can be any available media that can beaccessed by device 1200 and include both volatile and non-volatilemedia, and removable and non-removable media. Computer storage mediainclude volatile and non-volatile, and removable and non-removable mediaimplemented in any method or technology for storage of information suchas computer readable instructions, data structures, program modules orother data. Memory 1204, removable storage 1208, and non-removablestorage 1210 are all examples of computer storage media. Computerstorage media include, but are not limited to, RAM, ROM, electricallyerasable program read-only memory (EEPROM), flash memory or other memorytechnology, CD-ROM, digital versatile disks (DVD) or other opticalstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices, or any other medium which can be used tostore the desired information and which can be accessed by computingdevice 1200. Any such computer storage media may be part of computingdevice 1200.

Computing device 1200 may contain communications connection(s) 1212 thatallow the device to communicate with other devices. Computing device1200 may also have input device(s) 1214 such as a keyboard, mouse, pen,voice input device, touch input device, etc. Output device(s) 1216 suchas a display, speakers, printer, etc. may also be included. All thesedevices are well known in the art and need not be discussed at lengthhere.

In general, any device described herein may represent various types ofdevices, such as a wireless or wired phone, a cellular phone, a laptopcomputer, a wireless multimedia device, a wireless communication PCcard, a PDA, an external or internal modem, a device that communicatesthrough a wireless or wired channel, etc. A device may have variousnames, such as access terminal (AT), access unit, subscriber unit,mobile station, mobile device, mobile unit, mobile phone, mobile, remotestation, remote terminal, remote unit, user device, user equipment,handheld device, non-mobile station, non-mobile device, endpoint, etc.Any device described herein may have a memory for storing instructionsand data, as well as hardware, software, firmware, or combinationsthereof.

The in-band signaling and codec selection and deployment techniquesdescribed herein may be implemented by various means. For example, thesetechniques may be implemented in hardware, firmware, software, or acombination thereof. Those of skill would further appreciate that thevarious illustrative logical blocks, modules, circuits, and algorithmsteps described in connection with the disclosure herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

For a hardware implementation, the processing units used to perform thetechniques may be implemented within one or more ASICs, DSPs, digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, electronic devices, other electronicunits designed to perform the functions described herein, a computer, ora combination thereof.

Thus, the various illustrative logical blocks, modules, and circuitsdescribed in connection with the disclosure herein may be implemented orperformed with a general-purpose processor, a DSP, an ASIC, a FPGA orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general-purpose processor maybe a microprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

For a firmware and/or software implementation, the techniques may beembodied as instructions on a computer-readable medium, such as randomaccess RAM, ROM, non-volatile RAM, programmable ROM, EEPROM, flashmemory, compact disc (CD), magnetic or optical data storage device, orthe like. The instructions may be executable by one or more processorsand may cause the processor(s) to perform certain aspects of thefunctionality described herein.

If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes CD, laser disc, optical disc,digital versatile disc (DVD), floppy disk and blu-ray disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples described herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

Although exemplary implementations may refer to utilizing aspects of thepresently disclosed subject matter in the context of one or morestand-alone computer systems, the subject matter is not so limited, butrather may be implemented in connection with any computing environment,such as a network or distributed computing environment. Still further,aspects of the presently disclosed subject matter may be implemented inor across a plurality of processing chips or devices, and storage maysimilarly be effected across a plurality of devices. Such devices mightinclude PCs, network servers, and handheld devices, for example.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

1. A method of setting a codec for use by a first station incommunication with a second station, comprising: while on a call that issetup with the second station in a first codec mode and aninfrastructure running in the first codec mode, determining at the firststation whether the second station is equipped to run in a second codecmode; and instructing the second station to run in the second codec modeand setting the first station to run in the second codec mode, while theinfrastructure remains running the first codec mode, if it is determinedat the first station that the second station is equipped to run in thesecond codec mode.
 2. The method of claim 1, wherein determining at thefirst station whether the second station is equipped to run in thesecond codec mode comprises using in-band signaling.
 3. The method ofclaim 1, wherein determining at the first station whether the secondstation is equipped to run in the second codec mode comprisestransmitting in-band probe signals to the second station and receivingin-band acknowledgement signals from the second station.
 4. The methodof claim 3, further comprising transmitting the in-band probe signalsperiodically for a limited amount of time.
 5. The method of claim 3,wherein the first station is capable of generating, detecting, andreacting to in-band signals that are designed such that (a) the in-bandprobe signals are not received as any of the valid packets by a stationthat is unequipped to run in the second codec mode and (b) if thein-band acknowledgement signals are received by the first station, thefirst station determines that the transmission path is transcoding freeand the second station is equipped to run in the second codec mode. 6.The method of claim 1, wherein instructing the second station to run inthe second codec mode comprises sending instructions to the secondstation using in-band signaling.
 7. The method of claim 1, furthercomprising, while the first station is running the second codec mode,setting the codec at the first station to the first codec mode upondetection of a network transition from transcoder-free operation (TrFO)to non-TrFO during the call.
 8. The method of claim 1, wherein the firststation is mobile station.
 9. The method of claim 1, wherein the firststation is a terminating station for the call.
 10. The method of claim1, wherein the first station is an originating station for the call. 11.The method of claim 1, wherein the first codec mode is a narrowband modeand the second codec mode is a wideband mode.
 12. The method of claim 1,wherein the first station is a non-mobile station.
 13. An apparatus forsetting a codec for use by a first station in communication with asecond station, comprising: means for determining at the first stationwhether the second station is equipped to run in a second codec mode,while on a call that is setup with the second station in a first codecmode and an infrastructure running in the first codec mode; and meansfor instructing the second station to run in the second codec mode andsetting the first station to run in the second codec mode, while theinfrastructure remains running the first codec mode, if it is determinedat the first station that the second station is equipped to run in thesecond codec mode.
 14. The apparatus of claim 13, wherein the means fordetermining at the first station whether the second station is equippedto run in the second codec mode uses in-band signaling.
 15. Theapparatus of claim 13, wherein the means for determining at the firststation whether the second station is equipped to run in the secondcodec mode comprises means for transmitting in-band probe signals to thesecond station and means for receiving in-band acknowledgement signalsfrom the second station.
 16. The apparatus of claim 15, furthercomprising means for transmitting the in-band probe signals periodicallyfor a limited amount of time.
 17. The apparatus of claim 15, wherein thefirst station is capable of generating, detecting, and reacting toin-band signals that are designed such that (a) the in-band probesignals are not received as any of the valid packets by a station thatis unequipped to run in the second codec mode and (b) if the in-bandacknowledgement signals are received by the first station, the firststation determines that the transmission path is transcoding free andthe second station is equipped to run in the second codec mode.
 18. Theapparatus of claim 13, wherein the means for instructing the secondstation to run in the second codec mode comprises means for sendinginstructions to the second station using in-band signaling.
 19. Theapparatus of claim 13, further comprising, while the first station isrunning the second codec mode, means for setting the codec at the firststation to the first codec mode upon detection of a network transitionfrom transcoder-free operation (TrFO) to non-TrFO during the call. 20.The apparatus of claim 13, wherein the first station is mobile station.21. The apparatus of claim 13, wherein the first station is aterminating station for the call.
 22. The apparatus of claim 13, whereinthe first station is an originating station for the call.
 23. Theapparatus of claim 13, wherein the first codec mode is a narrowband modeand the second codec mode is a wideband mode.
 24. The apparatus of claim13, wherein the first station is a non-mobile station.
 25. Acomputer-readable medium comprising instructions that cause a computerto: determine at a first station whether a second station is equipped torun in a second codec mode, while on a call that is setup with thesecond station in a first codec mode and an infrastructure running inthe first codec mode; and instruct the second station to run in thesecond codec mode and set the first station to run in the second codecmode, while the infrastructure remains running the first codec mode, ifit is determined at the first station that the second station isequipped to run in the second codec mode.
 26. The computer-readablemedium of claim 25, wherein the instructions that cause the computer todetermine at the first station whether the second station is equipped torun in the second codec mode comprise instructions that cause thecomputer to use in-band signaling.
 27. The computer-readable medium ofclaim 25, wherein the instructions that cause the computer to determineat the first station whether the second station is equipped to run inthe second codec mode comprise instructions that cause the computer totransmit in-band probe signals to the second station and receive in-bandacknowledgement signals from the second station.
 28. Thecomputer-readable medium of claim 27, further comprising instructionsthat cause the computer to transmit the in-band probe signalsperiodically for a limited amount of time.
 29. The computer-readablemedium of claim 27, wherein the first station is capable of generating,detecting, and reacting to in-band signals that are designed such that(a) the in-band probe signals are not received as any of the validpackets by a station that is unequipped to run in the second codec modeand (b) if the in-band acknowledgement signals are received by the firststation, the first station determines that the transmission path istranscoding free and the second station is equipped to run in the secondcodec mode.
 30. The computer-readable medium of claim 25, wherein theinstructions that cause the computer to instruct the second station torun in the second codec mode comprise instructions that cause thecomputer to send instructions to the second station using in-bandsignaling.
 31. The computer-readable medium of claim 25, furthercomprising instructions that cause the computer to set the codec at thefirst station to the first codec mode upon detection of a networktransition from transcoder-free operation (TrFO) to non-TrFO during thecall, while the first station is running the second codec mode.
 32. Thecomputer-readable medium of claim 25, wherein the first station ismobile station.
 33. The computer-readable medium of claim 25, whereinthe first station is a terminating station for the call.
 34. Thecomputer-readable medium of claim 25, wherein the first station is anoriginating station for the call.
 35. The computer-readable medium ofclaim 25, wherein the first codec mode is a narrowband mode and thesecond codec mode is a wideband mode.
 36. The computer-readable mediumof claim 25, wherein the first station is a non-mobile station.
 37. Anapparatus for setting a codec for use by a first station incommunication with a second station, comprising: at least one processorthat determines at the first station whether the second station isequipped to run in a second codec mode, while on a call that is setupwith the second station in a first codec mode and an infrastructurerunning in the first codec mode, sends instructions to the secondstation to run in the second codec mode, and sets the first station torun in the second codec mode, while the infrastructure remains runningthe first codec mode, if it is determined at the first station that thesecond station is equipped to run in the second codec mode; and a memorycoupled to the at least one processor that stores a codec set comprisinga first codec associated with the first codec mode and a second codecassociated with the second codec mode.
 38. The apparatus of claim 37,wherein determining at the first station whether the second station isequipped to run in the second codec mode comprises using in-bandsignaling.
 39. The apparatus of claim 37, further comprising an in-bandsignal transmitter to transmit in-band probe signals to the secondstation, and an in-band signal receiver to receive in-bandacknowledgement signals from the second station, for use in determiningat the first station whether the second station is equipped to run inthe second codec mode comprises and receiving in.
 40. The apparatus ofclaim 39, wherein the in-band signal transmitter transmits the in-bandprobe signals periodically for a limited amount of time.
 41. Theapparatus of claim 39, wherein the first station is capable ofgenerating, detecting, and reacting to in-band signals that are designedsuch that (a) the in-band probe signals are not received as any of thevalid packets by a station that is unequipped to run in the second codecmode and (b) if the in-band acknowledgement signals are received by thefirst station, the first station determines that the transmission pathis transcoding free and the second station is equipped to run in thesecond codec mode.
 42. The apparatus of claim 37, wherein instructingthe second station to run in the second codec mode comprises sendinginstructions to the second station using in-band signaling via anin-band signal transmitter.
 43. The apparatus of claim 37, wherein theat least one processor sets the codec at the first station to the firstcodec mode upon detection of a network transition from transcoder-freeoperation (TrFO) to non-TrFO during the call, while the first station isrunning the second codec mode.
 44. The apparatus of claim 37, whereinthe first station is mobile station.
 45. The apparatus of claim 37,wherein the first station is a terminating station for the call.
 46. Theapparatus of claim 37, wherein the first station is an originatingstation for the call.
 47. The apparatus of claim 37, wherein the firstcodec mode is a narrowband mode and the second codec mode is a widebandmode.
 48. The apparatus of claim 37, wherein the first station is anon-mobile station.